1. Field of the Invention
This invention relates generally to an improved roofing material removal device. More particularly, the invention relates to an improved roofing material removal device that is mounted within a wheeled frame for removing a roof membrane and/or insulation layer from a roof and cutting case hardened steel screws and all types of mechanical fasteners.
2. Description of Related Art
There are two types of roofs that are most commonly seen today, low-slope and steep-slope roofs. Low-slope roofs are used mostly for commercial and industrial buildings; however, some residential buildings such as town homes and apartments will also use low-slope roofs.
Low slope roofs are also referred to as “flat roofs” although the roofs are not strictly flat. Most low-slope roofs have a small slope of about ¼ inch per foot, sometimes greater depending on the size of the building, to provide adequate drainage. Whenever a building does not have a proper drainage system, which will be discussed later, water tends to build up on the roof. Water buildup, or “ponding”, on the roof will cause the structure of the building to deflect and could lead to permanent structural damage of the building. Sagging roof joists will allow water to build up in the middle of the roof and make perimeter drains ineffective. If the structural deflection increases and is not prevented the overloaded structure could collapse. A puddle of water measuring 20 feet in width by 20 feet in length with 1 inch in depth will apply one time of weight pressure on the roof.
The membranes for low-slope roofs are divided into three general categories: the built-up roof membrane, the single-ply roof membrane, and the fluid-applied membrane.
Built-up roofing systems can be installed on buildings with either a concrete or a steel deck. Although the roofs are applied slightly different due to the nature of the roof deck there are similarities to their structure and material. Steel deck roofs start out with a layer of insulation boards that are mechanically fastened to the deck. Each of the four layers of the roof membrane, two layer of insulation, one of felt, and the final layer of aggregate (in that order), are held together by a layer of asphalt. The concrete deck roofs must have an asphalt primer applied before the first layer of asphalt can be put down. A layer of felt is then laid in place with another coat of asphalt on top with the insulation boards and final layer of aggregate put in place. The asphalt is used as a bonding agent on these roofs. If water or air gets trapped between layers of the membrane or between the sheathing and the membrane it will cause a blister to form, moving the gravel or aggregate and exposing the blister to ultraviolet or mechanical damage. A ruptured blister will create a crater that permits water penetration, which will eventually weaken and damage the roof.
The single-ply roofing membrane is a rapidly growing system today. These systems are installed in one single layer requiring less cost for labor time and materials. Single-ply roofs can be attached to a building by using several different methods: adhesives (cold or hot), ballast, fasteners that are hidden in the seams, or by mechanical fasteners that do not penetrate the membrane. Single-ply membranes can be either a large single “sheet” that once unfolded will cover the entire roof with no seams, or it can be separate rolls ranging from 3′ to 10′ in width, when once laid will have seams that must be sealed. The materials that are used for single-ply roofing systems are divided into two categories, thermoplastics and thermosetting. Hot air welding or solvent welding can join thermoplastic materials, however adhesives or pressure-sensitive tape must join thermosetting material. Thermoplastic materials are made up of the following: polyvinyl chloride (PVC), polymer-modified bitumens, PVC alloys, chlorinated polyethylene (CPE), polyisobutylene (PIS), and thermoplastic olefin (TPO). Thermosetting materials are made up of the following: ethylene propylene diene monomer (EPDM), chlorosulfonated polyethylene (CSPE), epichlorhydrin, and neoprene. PVC roofs may become brittle in cold weather especially if the membrane is tight. Shrinkage is another problem common with PVC roofs. It can cause separation from roof projections (plumbing vents or skylights) and edges. Some other problems caused by incorrect installation are wrinkles, ruptures, and “fishmouth” (separations at seams). Modified bitumen roof membranes must be protected from ultraviolet light by one of the following: a granular surface, a liquid coating (usually reflective), a foil surface, or ballast (usually gravel or aggregate), Ethylene propylene diene monomer (EPDM) roofs have a tendency toward thermal expansion and contraction. A tight EPDM roof may have problems around the perimeters and flashings where the membrane could pull away from its fasteners.
The fluid-applied membranes are mostly used for buildings with domes, shells, or unusual shapes. Either a roller or a spray gun, both of which usually require several coats, is used to apply this type of membrane.
Most low-slope roofs are covered with a ballast of either loose gravel or concrete blocks. The purpose of the ballast is to keep the membrane from being picked up by the wind, and to provide protection against the ultraviolet rays of the sun.
Membranes for low-sloped roofs are sealed at the edges by being glued to the parapet wall with fabric and mastic and covered by flashing. The parapet is part of the exterior wall that extends above the roof. The coping, or covering, of the parapet provides the final seal for the roof. It is designed with drip grooves along the edges to prevent water from running back under the coping and seeping into the membranes of the roof. A cant strip of wood or fiber is placed under the roof membrane along the edge of the roof and around any area of penetration (plumbing vents and skylights) to ease the bending so that it can be sealed to the wall. It also prevents standing water from collecting at the edge of the membrane.
There are two methods by which a low-sloped roof can be properly drained. One method of drainage is called Scuppers, which are placed along the edge of the building. A scupper is an opening in the parapet that allows water to drain off the edge of the roof into gutters and downspouts. Interior roof drains on the area of the roof provide the second and most common method of drainage. These drains are mechanically fastened at precise intervals to the roof of the building and are used to prevent the buildup of water as mentioned earlier. They are also covered with a strainer to avoid clogging of the drainage system.
Other features commonly found with low-sloped roofs are building separation joints and area dividers. The separation joint allows for the joining of separate parts of one structure or the joining of two structures that were built side by side. The joints are made to be flexible and waterproof so as not to tear and leak while allowing for the large differential movements between the adjoining parts. The purpose of the area divider is to allow for movement in the membrane itself and not the whole building. It is mostly used to divide a large roofing area to allow for thermal movement.
Single-ply low-slope roofing systems, “rubber roofs”, are becoming more widely used due to the ease of installations, lower labor cost, and they are less prone to leaks and cracks.
Impermeable rubber membranes positioned atop foam insulation is commonly used to make watertight roofs on commercial buildings. Over time, these membranes deteriorate, necessitating their periodic replacement.
Many roofing companies employ handheld tools to remove the weathered roofing membranes and foam insulation in order to minimize the likelihood of damaging roof decking plates and other roof features.